CTR

CTR is the percentage of people who saw an ad or link and clicked it.

CTR is a relevance signal before it's a performance signal. Ad platforms use it (alongside expected engagement and landing page quality) to help set Quality Score and Ad Rank — a higher CTR often means a cheaper CPC for the same auction position, because the platform is rewarding ads it predicts people will engage with.

A high CTR isn't automatically good. Clickbait-y creative can pull a high CTR from people who were never going to convert, which tanks your conversion rate and CPA even as the CTR chart looks great. Read CTR next to conversion rate, not alone — a lower CTR from better-qualified clicks is often the more profitable ad.